Ezine

Published: Aug 7, 2012

Author: Steve Down

Channels: Gas Chromatography

Sports supplements and dimethylamylamine

A drug initially introduced as a vasoconstrictor in the 1940s has gained notoriety in recent years due to its inclusion as an active ingredient in sports supplements backed up by claims that it is a natural ingredient. Those companies marketing the products refer to a paper published in 1996 which claimed to have discovered it in the geranium Pelargonium graveolens but a number of research groups have since cast doubt on that claim.

The drug in question is 1,3-dimethylamylamine (DMAA) also known as methylhexaneamine or geranamine. It is marketed as a central nervous system stimulant that can be used as a pre-workout supplement and a fat burner. Its stimulant properties resulted in its addition to the WADA List of Prohibited Compounds but its apparent toxic side effects are also causing concern. Just this week, the UK Food Standards Agency has advised consumers against eating products containing DMAA because it "has been linked with high blood pressure, nausea, cerebral haemorrhage, stroke and death."

Lately, research groups in Australia and the USA have reported that geranium oil does not contain DMAA, so any supplements claiming to contain "natural" DMAA is doing so falsely. Now, a further research group has published details of their work which appears to back up these claims by proving that DMAA in sports supplements is synthetic.

Daniel Armstrong and colleagues from the University of Texas at Arlington took advantage of the fact that DMAA is a stereoisomeric compound with two stereo centers, so it can exist as a mixture of up to four isomers in two pairs of enantiomers: the (R,R)- and (S,S)- and the (R,S)- and (S,R)-isomers.

In practice, natural compounds are often enriched in one type of enantiomer and would have characteristic ratios of diastereomers if they are present. In contrast, the compounds prepared by a particular synthetic procedure will have equal amounts of the enantiomers and will also have a characteristic diastereomeric ratio.

Stereoisomer ratios

Armstrong decided to measure the enantiomeric and diastereomeric ratios of synthetic DMAA and compare them with those of DMAA present in sports supplements. Two DMAA standards from different commercial sources were mixed with an amine internal standard and converted to the pentafluoropropionyl derivatives for analysis by GC-FID. Then, DMAA was extracted from 13 different sports supplements from a range of manufacturers and treated the same way.

A total of eight geranium oils were acquired from different manufacturers based in China and Egypt and extracted for analysis by LC/MS to see if DMAA was present in any of them. Two procedures were used involving underivatized and dansylated DMAA which were analysed on two different instruments, both using electrospray ionisation in the positive ion mode.

The underivatised samples were analysed on a linear ion trap using selected ion monitoring and the derivatised samples were taken to a triple quadrupole mass spectrometer for analysis using selected reaction monitoring.

DMAA missing in action - or not?

As expected, the commercial standards of DMAA existed as two pairs of enantiomers with equal amounts of isomer within each pair. The diastereomeric ratios from the two manufacturers were different at 1.22 and 1.42, suggesting that they were synthesised by different processes.

The concentrations of DMAA in the 13 supplements ranged from 0.1 to 11% and all of the diastereomeric ratios were in the same range as those of the synthetic samples. So, “it appears unlikely that the DMAA in supplements originates from natural sources such as geranium oils,” says Armstrong.

This conclusion is backed up by the analysis of the geranium oils because no DMAA was found in any of them, down to a detection limit of 50 ppb for the underivatized samples and 10 ppb for the derivatised samples.

In addition, they have funded new research that shows that DMAA and 1,4-dimethylamylamine have been isolated from geranium plants and measured using a fully validated method. This contradicts all of the reports which have shown the absence of DMAA in geranium oils.

However, Armstrong remains sceptical. He points out that the authors stated that the DMAA they isolated has two isomers which are present in equal amounts but that "their own data (chromatograms) seem not to support this statement as the peaks appear unequal. Also the fact that the DMAA diastereomer peaks were the same ratios in the synthetic standard as was found in the plant/oil extracts certainly raises a question in my mind," he told separationsNOW.com."

In addition, the amounts of DMAA found were at the ppb level, which would make it very difficult to extract economically at a commercial level. "In my opinion, the question of the presence of DMAA will come down to the integrity of the samples analyzed and possibly to how low can one push the detection limits."